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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'af9dc4faccd39475f9a4d502062b3fee32df9e38cb2833dae85d8b92ddd301db' 
  AND token = 'VBdGt2V85UEdYMfGSf6MEEKSQMJcwO4hh188pQgCmjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}